Download Mr. Williams CHEM I

Section 1
Organizing the Elements
Aristotle
Organized elements into
earth, air, water, fire, and
ether (celestial bodies).
Widely accepted for
centuries.
Organizing the Elements
By 1750, scientists had
identified 17 elements
with vastly different
properties
They wanted to devise
a system to organize
them based on
properties, but which
properties were most
important?
Antoine
Lavoisier
(1789)
Devised the first system
organizing elements into
metals, nonmetals, gases,
and earths
With the discovery of more
elements, this quickly lost
favor over the next 50 years
MENDELEEV BASED HIS PERIODIC TABLE
ON THE CARD GAME SOLITAIRE
HOW COULD WE ARRANGE THESE?
NUMBER?
RED
BLACK
COLOR?
DIAMONDS
SPADES
SUIT?
HEARTS
CLUBS
HEARTS
DIAMONDS
SPADES
CLUBS
CAN WE USE MORE THAN ONE SYSTEM?
HERE WE USE SUITS FIRST THEN ORGANIZE BY NUMBER WITHIN THE
COLUMNS
Mendeleev’s Cards
Mendeleev made a
card for each known
element
He put the name,
mass, and any known
properties
Special attention was
paid to reactions with
H and O
First he
arranged
them by mass
in rows
Then he arranged them into
columns as well so that
elements with similar
properties ended up in
columns together
PERIODIC TABLE - ARRANGEMENT OF ELEMENTS
INTO COLUMNS WHERE PROPERTIES REPEAT FROM ROW TO ROW
Mendeleev’s Predictions
Mendeleev realized
that there were likely
elements that had not
been discovered
He left holes where he
thought they should go
and even predicted
their properties
Eka-Aluminum
Mendeleev called the
element he thought
would go one spot
below aluminum, ekaaluminum
Prediction vs. Reality
EKA-ALUMINUM
Soft metal
Low
Melting
Point
Density =
5.9 g/cm3
Prediction vs. Reality
EKA-ALUMINUM
GALLIUM
Soft metal
Soft metal
Low
Melting
Point
Melting
Point - 29.7
C (85.46 F)
Density =
5.9 g/cm3
Density =
5.91 g/cm3
Further Discoveries
Within 20 years of his
first table, multiple
elements were
discovered with
properties exactly like
Mendeleev predicted
Germanium and
Scandium proved that
this table’s predictions
held true
THE MODERN PERIODIC TABLE
SECTION 2
The Modern Periodic
Table
The modern periodic
table is arranged by
atomic number, not
atomic mass (periodic
law)
Mendeleev was not
alive when it was
determined that each
element has a unique
number of protons
Periodic Law
The rows in the table
are called periods
The columns in the
table are called groups
or families
THE ARRANGEMENT OF THE PERIODIC TABLE DISPLAYS MANY
CHARACTERISTICS:
1) EACH PERIOD REPRESENTS ONE ENERGY LEVEL FOR ELECTRONS
2) THE BIG CHUNK OF 14 ELEMENTS HERE IS MOST OFTEN SHOWN
AS AN EXTRA TWO ROWS AT THE BOTTOM (LANTHANIDES AND
ACTINIDES)
3) ELEMENTS IN A GROUP HAVE MORE PROPERTIES IN COMMON
THAN ELEMENTS IN A PERIOD
Similarities of Elements
In this chunk of four
elements, lithium and
sodium share more
properties than lithium
and beryllium because
lithium and sodium are
in the same group
PRACTICE - WHICH TWO ARE THE MOST SIMILAR?
A) COPPER AND ZINC B) SULFUR AND BROMINE C) SODIUM AND CALCIUM D) ALUMINUM AND GALLIUM
A sample
Periodic Entry
Atomic Number - 8
Atomic Mass - 15.99
Chemical Name - Oxygen
Chemical Symbol - O
ATOMIC NUMBER SHOWS PROTONS (AND ELECTRONS IF ATOM IS NEUTRAL)
ATOMIC MASS (ROUNDED) SHOWS PROTONS + ELECTRONS
ATOMIC MASS (ROUNDED) - ATOMIC NUMBER = NEUTRONS
OXYGEN HAS 8 PROTONS (ATOMIC NUMBER) 8 ELECTRONS (ATOMIC
NUMBER) AND 8 NEUTRONS (15.999 ROUNDED TO 16 - 8 = 8)
Natural vs. Man-made
There are 90 naturally
occurring elements
and 28 man-made that
we know of
The man-made are
usually written in an
outline form
Tc (43), Pm (61) and
anything past 92 are all
man-made
Element Class
By looking at the
location on the
periodic table, you can
determine if the
element is a:
metal
non-metal
metalloid
NOTE THE PURPLE STAIR STEP
IT DIVIDES METALS AND NON-METALS WITH THE EXCEPTION OF HYDROGEN (NON-METAL)
METAL
METALLOID
NON-METAL
Metals
Conduct electricity and heat,
all but mercury are solid,
malleable (hammered
without shattering) and
ductile (made into wires)
Some are extremely reactive, others barely react at all
Fe, Mg, Cu and multiple others will all react with oxygen in the air
Au will just sit outside basically forever and not do anything
Transition Metals
Large chunk of 10
columns of 4 elements
that bridge the two
sides of the table
Many very common
metals, including Fe,
Hg, Cu, Au, Ag, Pt, Ni,
Ti and more
Lanthanides and
Actinides also count
here
Non-Metals
Opposite properties of
metals
Poor conductors of
heat and electricity
Mostly gas at room
temp and solids are
brittle
Extremely variable
properties
Metalloids
Metalloids are kind of
metal, kind of not.
Their properties vary
and often are
dependent on their
temperature. Metalloids include:
B, Si, Ge, As, Sb, Te,
Po, At (some argue Al
but it is usually
considered a metal)
Periodic Trends
Within a period, the farther left is most metallic and
farthest right is most non-metallic
Many other trends will be discussed in the future and in
chemistry
Review
Which subatomic particles
determine the atomic mass of an
atom?
How many periods does the
periodic table have?
An element that is shiny and
conducts electric current is likely
to be a ____________.
An atomic mass unit is based on
the mass of which element?
In the modern periodic table,
elements are arranged in order of
________________.
1.What fact most influences
today’s periodic table that
Mendeleev did not know
about when making his?
2.What’s the deal with the two
floating rows at the bottom
of the periodic table?
3.What three major categories
are used to classify the
elements?
4.What information can you
get from the periodic table
about class, phase, and
subatomic particles? How
do you know?
THE REPRESENTATIVE GROUPS
SECTION 3
Valence Electrons
Electrons on the
outermost shell
Remember the 1st ring
holds 2, 2nd and 3rd
ring hold 8, and the 4th
ring holds more but if
we stop at calcium, it’s
2
The properties of an
element depend largely
on their valence
electrons
Representative Groups
The tall 8 columns (1A
-8A) are known as the
representative groups
In these groups, all
elements have the
same valence
electrons (with the only
exception of He)
VALENCE ELECTRONS = COLUMN #
ON FOR REPRESENTATIVE ELEMENTS! HE HAS TWO VALENCE ELECTRONS
The Alkali Metals
H is not a metal but
belongs here based
on its valence
electrons
Soft metals that oxidize
(tarnish) in air
They do not exist
naturally in their
Every element in this elemental form; only in
group has one
compounds
valence electron
The Alkaline Earth
Metals
2 valence electrons
each
Much harder than
alkali metals with
higher melting points
Mg is part of the plant
pigment chlorophyll which
helps capture light for
photosynthesis
Calcium is necessary for
bones and teeth as well as
Most important for life: chalk, coral, toothpaste
Magnesium and
and oyster vomit (pearls)
Calcium
The Boron Family
Aluminum is the most abundant metal in the
Earth’s crust
It comes from the mineral bauxite
Recycling aluminum takes much less energy than
extracting it from bauxite
Boron is in cleaners and silly putty
The Carbon Family
All life on Earth is carbon based
Nearly every chemical in your body, except water,
has carbon in its formula
Coal and diamonds are both examples of pure C
This group has the most wide ranging properties
of any as it has a non-metal, two metalloids, and
two metals and metallic properties increase as you
go down the column
Silicon
Second most abundant
element on Earth’s crust
(behind oxygen)
It is in glass, sand, clay,
and computer parts
The Nitrogen Family
Five valence electrons
Nitrogen is the backbone of all proteins and
therefore life
Nitrogen and phosphorus are good for fertilizers
Phosphorus exists as both white (extremely
explosive) and red phosphorus (matches)
The Oxygen Family
Oxygen is the most abundant element in the
Earth’s crust
Six valence electrons
1st of 3 groups without a metal
All life needs oxygen in some form (at least water)
OZONE IS THREE OXYGEN ATOMS BOUND TOGETHER
IT PROTECTS US FROM UV BUT SOME MANMADE CHEMICALS CAN DEPLETE THIS LAYER OF ATMOSPHERE
We have a
large amount
of sulfur in
the US
The #1 chemical produced
in the US is sulfuric acid for
fertilizer and chemical
research
In Louisiana, the town of
Sulphur has large deposits
The Halogens
7 valence electrons
Fluorine - used in
toothpaste; most
electron negative
element (reactive)
Chlorine - poisonous
green gas used in
WWI warfare, killing
bacteria in pools and
drinking water and
bleach
Iodine - needed to
keep your thyroid
working - usually
comes from seafood
but US government
also adds it to table
salt
The Noble Gases
All have 8 valence except helium (2)
All have a filled outer shell which makes them
extremely non-reactive
Neon lights actually can be filled with any of the
gases except radon (radioactive)
Argon is often used to fill containers that need to
be oxygen free (like cesium from the alkali metals)